The application of hydroprocessing on the fossil fuels in the petroleum industry is to produce fuels with low content of sulfur, metals, and nitrogen. Because crude oils are formed by a mixture of complex hydrocarbons, the rate of reactions is the controlling step in these processes, thus, it is important to have a relatively large accessible specific surface area catalyst (more catalytic sites in a given volume) in order to allow for the most effective use of reactor volume. This in turn requires the entire volume of the support or catalyst is made of material with high-surface-area material, and the pore structure of the material is such that the reactants can diffuse into and products can diffuse outside the volume of the catalyst effectively over relatively long distances. The catalysts used have a variety of shapes (e.g., pellets, pills, beads, rings, tri-lobes, etc.) and are generally formed of alumina as catalysts or catalyst support for using in catalytic reactions. These structures are typically formed by extrusion of alumina or other selected oxides, followed by drying and calcining. However, beds packed with pellets tend to exhibit relatively high resistance to flow and also develop preferential flow paths, which is particularly important in the case of complex feed of heavy fractions and residues. The method of support preparation (silica-alumina and zeolite-alumina) usually affects the physical and chemical properties of the catalysts such as cracking activity, textural properties and mechanical strength of support or catalyst. The mixed oxide, silica-alumina in the present invention is used as support for hydroprocessing particularly in catalytic reactions that need acidic catalysts, or can optionally be combined with zeolites, and other inorganic oxides.
The present invention provides a method of synthesis of support for hydroprocessing catalyst either amorphous SiO2—Al2O3 at various SiO2/Al2O3 ratios or ultra-stable Y zeolite with alumina, which creates acidic sites and enhances catalyst activity of hydrocracking which significantly improves the yields of lower boiling point fractions. The use of such supports and catalysts and methods for their preparation are described in the following patent literature.
U.S. Pat. No. 4,289,653 reports the preparation of a support extruded catalyst by mixing aluminum sulfate and sulfuric acid with sodium silicate to form a silica sol in an alumina salt solution (pH≈1-3), a further increase in pH of 7 to 8 by adding NH4OH forms a co-gelled mass. The co-gelled mass is mulled with peptizing agent, a metal from Group VIB and Group VIII to form a paste which can be extruded, dried and calcined. The catalyst is used for the denitrification of middle distillates.
U.S. Pat. No. 4,988,659 deals with the preparation of a silica-alumina matrix by a method which comprises mixing a silicate solution with an aqueous solution of an acid aluminum salt to a pH range of 1 to 4; slowly adding a base at high stirring, and adjusting the said slurry to a pH range of 5 to 9; aging the said co-gel at a temperature from ambient to 95° C. The co-gelled mass is spray dried and calcined and subsequently these catalysts are tested in Fluid Catalytic Cracking (FCC) process units to conversion of hydrocarbon feeds to produce high octane gasoline.
U.S. Pat. No. 3,974,099 describes a silica-alumina co-gel prepared from a mixture of sodium silicate and sodium aluminate. The resultant gel is acidified and alumina is precipitated by reaction with excess sodium aluminate in the reaction mixture. The dried gel is exchanged with ammonium sulfate to reduce the Na2O content to less than 1%.
U.S. Pat. No. 3,423,332 states an improved cracking catalyst that can be produced from a commercial silica-alumina gel catalyst containing 13% Al2O3. The product is activated by digestion of a gel at a high pH and elevated temperature to produce an amorphous product. The sodium content of the product is reduced by cations exchange such as Ca, Mg, NH4 and rare earth.
U.S. Pat. No. 3,974,099 describes the preparation of highly active amorphous silica-alumina catalysts. The catalysts may contain substantial quantities of alumina.
U.S. Pat. No. 3,459,680 reports the preparation of hydrocarbon conversion catalysts containing zeolite dispersed in an inorganic oxide matrix. The matrix may include silica-alumina-rare earth oxide components.
U.S. Pat. Nos. 4,238,360, 4,246,138 and 4,264,474 describe the preparation of silica-alumina gels and catalysts which are exchanged with solutions of rare earth salts. The resulting catalysts are used in the conversion of hydrocarbons.
U.S. Pat. No. 4,111,846 presents the preparation of hydrosols and catalysts wherein an alkali metal silicate solution reacts with a mixture of titanium and aluminum salts. A mix pump is used to rapidly and efficiently combine the silicate and mixed salt solutions.
U.S. Pat. No. 4,289,653 deals with the preparation of silica hydrosols that are used as binders in the manufacture of particulate cracking catalysts. The silica sol contains salts of titania, zirconia, iron or ceria which modify the physical and/or catalytic characteristics of the catalyst.
U.S. Pat. No. 6,902,664 describes the preparation of a catalyst whose composition comprises a low acidity using a certain amount of highly dealuminated ultra stable Y zeolite. The invention discloses a process for converting hydrocarbonaceous oils comprising the catalyst with metals Mo (W), Ni, Co, Pt, Pd and their mixture thereof. The process is mainly applied for lube hydroprocessing in a single as well as two-stage hydrocracking.
U.S. Pat. No. 6,995,112 presents the preparation of amorphous silica-alumina hydrosols which are used as lube oil hydrofinishing process to produce lubricating oil base stock.
U.S. Pat. No. 4,600,498 describes a catalyst containing hydrogenation metals supported on a base having (1) a crystalline alumino-silicate zeolite, which has cracking activity, and (2) a dispersion of silica-alumina in an alumina matrix which is employed for mild hydrocracking of vacuum gas oil.
U.S. Pat. No. 3,130,007 reports synthesis of pure Y zeolite with a number of modifications, one of which is ultra-stable Y zeolite as described in U.S. Pat. No. 3,536,605. The Y Zeolite has been constantly improved by techniques like ammonium ion exchange, de-alumination conditions, acid extraction of octahedral aluminium, and various forms of drying and calcination in order to enhance the performance of the hydrocracking catalysts.
U.S. Pat. No. 3,835,027 describes a catalyst containing at least one amorphous refractory oxide, a crystalline zeolitic aluminosilicate and a metal component for hydrogenation selected from the Group VI and VIII and their sulfides and oxides. The patent revealed that the added crystalline zeolite enhances the catalytic and denitrogenation activity of the catalyst.
U.S. Pat. No. 4,857,171 reports a process for converting hydrocarbon oils comprising contacting the oil with a catalyst which consists essentially of a Y zeolite, a silica based amorphous cracking component, a binder and at least one hydrogenation metal component selected from the Group VI and/or a Group VIII metal and mixtures thereof.
U.S. Pat. No. 4,419,271 discusses a composition useful as a catalyst base for supporting active hydrogenation metal components or to carry out hydrocarbon conversion by acidic catalysts, comprising an intimate heterogeneous mixture (1) Y zeolite modified by crystalline alumino-silicate (2) silica-alumina dispersed in a gamma alumina matrix.
EP 0162,733 (U.S. Pat. No. 4,738,940) reports the use of Y zeolite as a catalyst component for hydrocracking which has a narrow pore diameter distribution, that means at least 80% of the total pore volume is made up of pores having a diameter of less than 2 nm, being approximately 85% of total volume.
GB-A-2114594 Patent describes a process for the production of middle distillates using a catalyst comprising the so-called expanded pore faujasitic zeolites. The pore expansion referred in the said patent specification has been obtained by contacting faujasitic zeolite with steam at different temperature, followed by contacting the steamed faujasitic zeolite with an acid, preferably an acid having a pH less than 2.
U.S. Pat. No. 6,399,530 reveals the preparation of an acidic amorphous silica-alumina catalyst that has a large pore volume. The acidic component is inserted by using silica-alumina in a modified Y zeolite. The catalytic activities were evaluated for hydrocracking of vacuum gas oil to produce middle distillates. The amorphous silica-alumina has a SiO2 content of 10-50 wt. %, a specific surface area of 300-600 m2/g, and a pore volume of 0.8-1.5 ml/g.
Examples of the above patents are representative of the state-of-the-art related catalyst formulations and other catalyst useful components along with their process conditions. Most of the catalysts are used for light feedstock hydroprocessing and the method of support and catalyst preparation and its composition are entirely different than those of the catalysts of the present invention.
The present invention is better compared with the above said references due to providing a catalyst having large pore diameter and bi-functional in nature (i.e., hydrocracking and hydrogenation), which contributes the composition of the support (acidic) as well as active metal sites. The present patent also supplies a procedure in order to obtain a catalyst and its synthesis. Thus, one object of the present invention is to provide a method of synthesis.
Therefore, the objective of this invention is to produce a catalyst for hydrocracking of heavy crude oil along with high metal retention capacity during the hydroprocessing of heavy oil and residue as well as providing a long unit life and upgraded oil.
Another objective of the present invention is to develop a procedure for a catalyst having acidic component (hydrocracking function) and large pore diameter to remove effectively metals (Ni+V), sulfur, nitrogen contaminants in order to protect fast deactivation of catalyst. The present modified support materials have proven to be superior for organic compound conversion reactions. Such modified materials, the method of their modification and their use in heavy oil conversion are not so far disclosed.